1. Field of the Disclosure
The present disclosure relates generally to cellular communication networks and, more particularly, to manual public land mobile network (PLMN) selection in cellular communication networks.
2. Description of the Related Art
The 3GPP specification (in particular, 3GPP spec 23.122, section 4.4.3.1.2) enables a user to select a PLMN for user equipment (UE) operation, in a manual mode. In the manual mode, the UE must select the user selected PLMN and the UE must register with the user selected PLMN. If there is no selected PLMN or registered PLMN, the UE will either display a list to the user and remain in limited service or select the home PLMN (HPLMN) if available (provided the UE is powered on).
However, 3GPP does not handle all possible critical scenarios. For example, if a particular device A with a first universal integrated circuit card (UICC), UICC A is being used, the user of device A performs a manual search and selects PLMN A. The device A gets registered on PLMN A. The user of device A inserts a second UICC, UICC B in device A. The device will power on in manual mode and may go to a limited state (if UICC B has no registered PLMN (RPLMN)) or display a list of possible PLMNs to the user, which the user may ignore. The device A may remain in a “no service” state, with the UICC B.
In another case, the user may insert UICC A after manual selection and registration into device B. In this case, the device B will operate in its current mode, which may be an automatic mode and automatically select a PLMN. The user may be required to pay an additional fee, if his previous desired PLMN is not selected.
For example, a user may select PLMN X manually using an international mobile subscriber identity (IMSI) XX in UICC A in a roaming area to minimize the call and data charges and the device is registered successfully with the PLMN X. Then, the user may insert the UICC A (IMSI A) in a different device and powers the device on. Since that device was operating in automatic mode and an RPLMN was not available temporarily, this device selects a different PLMN of which the user was not aware. Unaware of the current registered PLMN, the user may be charged significantly as the UE is using a circuit switched (CS) call and packet switched (PS) data on a different PLMN in roaming.
As another example, a user selects PLMN X manually with the UICC A in a roaming area to minimize the call and data charges on a device A and the registration of the device with the PLMN X is successful. Then, the user inserts another UICC B in device A. Since device A was operating in manual mode and the RPLMN in UICC B is invalid, the UE will go to limited service and remain in limited service until the user changes to automatic mode and selects a new PLMN. If the user does not notice or cancels the PLMN list, the UE will remain in limited service.